The present invention relates to a semiconductor integrated circuit which is mountable on a recording device such as a drive recorder and a method of operating the same, and particularly to a technology which is effective to reduce the processing load and power consumption when recording video images of a large number of subjects moving from generally the center of the image toward the peripheral part of the image.
Conventionally, when an accident of a vehicle such as an automobile occurs, it is not rare that a dispute with regard to fact finding associated with the accident arises among the parties concerned. It often happens that allegations of the parties concerned conflict as to whether the traffic signal was green or red, or whether there was a sudden dash.
An aircraft, in contrast, has mounted thereon a driving situation recording device called a flight recorder, and data of the recorded driving situation is used as important evidence when investigating the cause of an aircraft accident.
Accordingly, as with the flight recorder equipped in an aircraft, there has been proposed a drive recorder also for a vehicle such as an automobile, which records a few dozen seconds long video before and after an accident occurs, in place of an eyewitness at the time of the accident.
For example, the drive recorder records digital video signals and digital audio signals as drive recorder information respectively output from a vehicle-mounted camera and a vehicle-mounted microphone to a hard disk drive (HDD) of a vehicle-mounted recording medium.
The following patent document 1 (Japanese Patent Laid-Open No. 2005-323021) describes, for a vehicle-mounted imaging system which captures images of a subject in front of the running direction while the vehicle is running in which an object included generally in the center of an image captured at the current capture timing appears at the next capture timing as an enlarged object that has been moved toward the peripheral part of the image, detecting an optical flow of the stationary subject using the moving speed of the vehicle detected by a vehicle speed detecting unit, moving respective objects included in the images captured by the imaging system using the optical flow, and compressing the images by calculating the difference between the image in which the object has been moved and the image in the next frame.
The vehicle-mounted imaging system described in the following patent document 1 includes a characteristic point extraction unit and an positioning unit so that the characteristic point extraction unit extracts a characteristic point of the image in which the object has been moved and a characteristic point of the image in the next frame, and the positioning unit moves the object again in order to position the characteristic points, extracted by the characteristic point extraction unit, of the image in which the object has been moved. Included in the characteristic points extracted by the characteristic point extraction unit are: edges, particular straight lines and curves, particular shapes, or regions having particular colors.